Green-Duwamish River

Washington

Map of the Duwamish/Green River watershed with the Green River highlighted

Seattle may be surrounded by water, but the Green-Duwamish is the city’s only river. The Green flows out of the Cascade Mountains just north of Mount Rainier, through Flaming Geyser State Park, and down to Elliott Bay through communities including Auburn, Kent, and Tukwila.

At Tukwila the Green turns into the Duwamish River, where there was once a confluence with the since-rerouted Cedar and Black rivers.

Threats and Opportunities

The Green River Valley – where Kent and Auburn are located – is home to the second largest warehouse district on the West Coast. Below that, the Duwamish is an industrial river that feeds into the heart of the Port of Seattle.

Up higher in the system, threatened salmon and steelhead are effectively blocked from the river’s headwaters by Howard Hanson Dam, a flood control structure that lacks a passage system for outmigrating juvenile salmon. An adult fish passage system at Tacoma Water’s diversion dam just downstream is essentially useless until juvenile fish passage is constructed at Howard Hanson Dam.

American Rivers is working to integrate improvements to river habitat in the lower Green/Duwamish with fish passage in and out of the river’s headwaters.

In the lower Green River, we are focusing on ensuring that the Green River System-Wide Improvement Framework process currently underway includes a robust plan to restore and broaden significant portions of the Green’s highly developed floodplain, as well as provide for planting trees along the river to reduce water temperatures that currently can be deadly for adult salmon returning upriver to spawn.

In the upper Green, we are fighting for a juvenile fish passage system to be installed at the U.S. Army Corps of Engineers’ Howard Hanson Dam, a flood control project that also helps store water for the City of Tacoma’s water supply. This fish passage system was supposed to be complete by the early 2000s, but it is still sitting on the drawing board without funding.

Funding floodplain restoration makes more sense with juvenile fish passage and vice versa – each project makes the other a more valuable investment.

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